Design method of aerial oil drainage channel for draining oil through aircraft pelvic fin

Abstract

The invention discloses a design method of an aerial oil drainage channel for draining oil through a ventral fin of an airplane. A, selecting an oil tank as an oil drain tank, and installing an oil delivery pump in the oil drain tank; b, an oil pipe extends out of the oil drainage tank to serve as an engine body oil drainage pipeline, and an oil drainage stop valve is installed on the engine body oil drainage pipeline; c, arranging and fixing an engine body oil drainage pipeline along an engine body frame, and butting an outlet of the engine body oil drainage pipeline with an inlet of a pelvic fin oil drainage channel (2) in the pelvic fin at a root rib of the pelvic fin (1) through a flange; d, according to the requirement of the oil drainage speed, the internal sectional area requirements of an engine body oil drainage pipeline and a pelvic fin oil drainage channel are calculated; and e, designing the outlet of the ventral fin oil drainage channel at the rear edge of the ventral fin. The problem of aerial oil drainage of an airplane without a wing oil tank is solved, and therefore various requirements for faults, warning and the like after the airplane takes off are met.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft aerial oil discharge, and in particular relates to a method for designing an aerial oil discharge channel for discharge oil through an aircraft ventral fin. Background Art

[0002] Aerial fuel dumping refers to the discharge of excess fuel from the aircraft during flight after takeoff, so that the total weight of the aircraft is not greater than the maximum landing weight required for return flight, thereby coping with various needs such as onboard faults and alarms. It is an important function that is currently indispensable for all types of aircraft.

[0003] At present, all kinds of civil aircraft release fuel in the air mostly through the drain port at the wing tip, that is, an oil drain port is arranged at the trailing edge of the wing near the wing tip, and the oil drain port is connected to the wing fuel tank to achieve the purpose of draining fuel. This method is the most common, but requires the aircraft to have wing fuel tanks; there are also a few aircraft whose oil drain ports are arranged near the end of the tail nozzle. This method can easily cause the fuel released from the oil drain port to be ignited by the high-temperature tail flame of the turbojet engine, which is risky and requires extremely high fire protection design near the aircraft tail nozzle and engine compartment. Summary of the invention

[0004] The purpose of the present invention is to provide a method for designing an aerial oil discharge channel for oil discharge through the aircraft ventral fin. The present invention solves the aerial oil discharge problem of aircraft without wing oil tanks, thereby meeting various requirements such as faults and alarms after the aircraft takes off.

[0005] The technical solution of the present invention is: a method for designing an aerial oil discharge channel for discharging oil through the ventral fin of an aircraft, comprising the following steps:

[0006] a. Select an oil tank as the oil drain tank and install an oil pump in the oil drain tank;

[0007] b. Extend the oil pipe from the oil drain tank as the engine body oil drain pipeline, and install an oil drain cut-off valve on the engine body oil drain pipeline;

[0008] c. Arrange and fix the engine body oil drain pipeline along the engine body frame, and connect the outlet of the engine body oil drain pipeline to the inlet of the ventral fin oil drain channel in the ventral fin through a flange at the root rib of the ventral fin;

[0009] d. Calculate the internal cross-sectional area requirements of the fuselage oil discharge pipeline and ventral fin oil discharge channel according to the oil discharge speed requirements;

[0010] e. Design the outlet of the ventral fin oil drain channel at the rear edge of the ventral fin.

[0011] In the aforementioned method for designing an aerial oil discharge channel for discharging oil through the aircraft ventral fin, in step c, when the fuselage oil discharge pipeline is arranged and fixed along the fuselage frame, the distance between two adjacent stress points on the fuselage oil discharge pipeline is not greater than 700 mm.

[0012] In the aforementioned method for designing an aerial oil discharge channel for draining oil through the aircraft ventral fin, in step c, when the fuselage oil discharge pipeline needs to pass through the fuselage reinforcement frame, a hole is opened in the reinforcement frame, and the fuselage oil discharge pipeline passes through the reinforcement frame and is fixed by a flange.

[0013] In the aforementioned method for designing an aerial oil discharge channel for discharging oil through the aircraft ventral fin, in step c, when the fuselage oil discharge pipeline needs to pass through the ordinary frame and / or half frame of the fuselage, the ordinary frame and / or half frame are locally reinforced or overall reinforced, and the fuselage oil discharge pipeline is connected to the ordinary frame and / or half frame through a clamp.

[0014] In the aforementioned method for designing an aerial oil discharge channel for discharging oil through the aircraft ventral fin, in step c, the ventral fin oil discharge channel and the ventral fin are designed in a fusion style.

[0015] In the aforementioned method for designing an aerial oil discharge channel for discharging oil through the aircraft ventral fin, in step c, the ventral fin oil discharge channel is in a downward tilt state as a whole, and the downward tilt angle is 3 to 6 degrees.

[0016] In the aforementioned method for designing an aerial oil drain channel for draining oil through the aircraft ventral fin, in step e, a titanium alloy oil drain port is designed at the outlet of the ventral fin oil drain channel at the trailing edge of the ventral fin.

[0017] In the aforementioned method for designing an aerial oil discharge channel for discharging oil through the aircraft ventral fin, the length of the titanium alloy oil discharge port is 8 to 15 cm.

[0018] The advantages of the present invention are:

[0019] (1) Solve the need for mid-air fuel dumping of aircraft without wing fuel tanks, especially those with slower flight speeds, to meet emergency landing requirements;

[0020] (2) The fuel released from the ventral fin is far away from the engine tail flow and is not easily ignited by the engine tail flame, which is safer;

[0021] (3) The ventral fin is designed as an aluminum alloy wing structure with a ventral fin oil drain channel in the middle. That is, the ventral fin oil drain channel is designed to be co-shaped with the ventral fin, and the passage in the middle of the ventral fin is used as the last section of the oil drain pipeline. Compared with adding an oil drain pipe outside the ventral fin or burying the oil drain pipe in the ventral fin structure, this form can not only reduce the empty weight of the aircraft, but also does not require the oil drain pipe in the ventral fin to be disassembled and installed separately, greatly reducing the installation and maintenance work of the rear section of the oil drain pipe, and is also more beautiful;

[0022] (4) The root rib of the ventral fin is connected to the outlet of the fuselage oil drain pipeline by a flange. Specifically, the flange of the fuselage oil drain pipeline is sealed and connected in the middle by a circle of complete rubber gasket + self-locking bolts on the outside of the fuselage. This structure can not only install the ventral fin (with a ventral fin oil drain channel in the middle), but also fix the outlet of the fuselage oil drain pipeline through the ventral fin; it avoids the need to open a cover on the rear fuselage side wall near the root rib of the ventral fin, which increases the complexity of the fuselage design and the disassembly and assembly process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the ventral fin structure of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific settings and methods proposed below, but covers any improvements, replacements and modifications of structures, methods, devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity in the present invention.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] Example 1. A method for designing an air oil discharge channel for discharging oil through the aircraft ventral fin, such as Figure 1 As shown, the following steps are included:

[0028] a) Select an oil tank as the oil drain tank, and install the oil pump and internal pipelines in the oil tank;

[0029] b) Extend the oil drain pipe from the oil drain tank. To start and end the oil draining task, install an oil drain cut-off valve on the oil drain pipe;

[0030] c) The fuselage oil drain pipeline is arranged and fixed along the fuselage frame. During the oil draining process, the inside of the fuselage oil drain pipeline will be filled with fuel. In order to prevent the vibration during flight from causing the pipeline or fuselage structure to rupture, it is necessary to disperse the stress points on the fuselage oil drain pipeline. The distance between two stress points should not be greater than 700mm. The specific method is to open a hole in the reinforced frame, and the fuselage oil drain pipeline passes through the reinforced frame and is fixed with a flange. The ordinary frame and half frame are partially or overall reinforced, and the fuselage oil drain pipeline is connected to the ordinary frame and half frame through a clamp. Finally, the fuselage oil drain pipeline extends to the rib of the ventral fin 1, and the connection end face of the fuselage oil drain pipeline at the root of the ventral fin 1 (i.e., the outlet end face of the fuselage oil drain pipeline) adopts a flange plate;

[0031] d) Calculate the internal cross-sectional area requirement of the oil discharge pipeline of the engine body according to the oil discharge speed requirement;

[0032] e) Design of oil drain pipe in ventral fin section: If an oil drain pipe is added to the outside of ventral fin 1, the protrusion on the surface will increase the flight resistance and reduce the aerodynamic efficiency of the ventral fin, and the aesthetics will also be reduced; if the oil pipe is buried inside the ventral fin, due to the low structural height of the ventral fin itself (i.e. the thickness of the ventral fin when viewed from the front), the oil drain pipe is difficult to disassemble inside the ventral fin (unless the ventral fin is designed to be disassembled into two pieces, but this solution will greatly reduce the strength of the ventral fin and increase the useless empty weight, and cause coupling between the disassembly of the ventral fin and the disassembly of the oil drain pipe. Even if only one of them needs to be disassembled, the other needs to be completely disassembled); therefore, the ventral fin is designed as an aluminum alloy wing surface structure with a passage in the middle, and the passage in the middle of the ventral fin serves as the last section of the oil drain pipe, i.e., the ventral fin oil drain channel 2. In order to solve the problem of difficult disassembly and assembly, the root rib of the ventral fin and the flange of the oil drain pipe are sealed and connected in the middle by a circle of complete rubber pads + self-locking bolts on the outside of the fuselage. In this way, the end of the oil drain pipe (flange) located at the rear section of the fuselage can be fixed through the outside of the ventral fin.

[0033] f) The tail end (exit) of the ventral fin oil discharge channel 2 should be located at the rear edge of the ventral fin and should not be designed at the lower edge of the ventral fin, otherwise it will have an adverse effect on the aircraft's ground-rubbing angle, and the fuel adhering to the lower edge of the ventral fin will increase the risk of burning the lower edge of the ventral fin;

[0034] g) The cross-sectional area of ​​the ventral fin oil discharge channel 2 shall not be less than the requirement of item d). The angle between the ventral fin oil discharge channel 2 and the horizontal plane is 3 to 6 degrees, and the ventral fin oil discharge channel 2 is slightly inclined downward. This can not only make the fuel discharged from the rear edge of the ventral fin when the aircraft is draining fuel in the air flow directly backward under the combined influence of gravity, aerodynamic force and engine wake, without adhering to the rear edge and lower edge of the ventral fin, but also make the residual fuel in the oil discharge pipeline be discharged under the action of gravity when the aircraft is parked, so as to prevent the pipeline from being contaminated for a long time;

[0035] h) A titanium alloy oil drain port 3 about 10 cm long is installed at the tail end of the oil drain passage to deal with the situation where the fuel burns accidentally (because this is the part closest to the engine tail flame and the temperature is high, there is a small risk that the fuel will burn here. The titanium alloy material is resistant to high temperature and ablation. The flame only burns here and will not affect the ventral fin and the body structure). The inner diameter of the oil drain port matches the internal cross-sectional area of ​​the oil drain pipe, and the angle is consistent with the oil drain passage inside the ventral fin.

[0036] Example 2. A method for designing an aerial oil discharge channel for discharging oil through the aircraft ventral fin:

[0037] a) A requirement is put forward for an aircraft to release fuel in mid-air, requiring X liters of fuel to be released within X minutes;

[0038] b) Select the No. 1 fuel tank of a certain aircraft as the fuel drain tank, and install the XX-A type fuel pump and internal fuel pipeline in the fuel tank;

[0039] c) According to the oil delivery capacity of the oil delivery pump and the requirements in a), the oil discharge flow rate is calculated to be approximately X liters / minute. From this, the inner diameter of the oil discharge pipeline should be no less than 0.001m 2 Therefore, the flow area of ​​the oil discharge path in the ventral fin should not be less than 0.001m 2 ;

[0040] d) Design the structure of the ventral fin, which is an aluminum alloy wing structure with a passage in the middle. The cross-sectional area of ​​the passage is 0.001m 2 ;

[0041] e) The angle between the main oil discharge channel in the ventral fin and the horizontal plane is about 4 degrees. The tail end of the oil discharge channel is tilted downward. A 10cm long titanium alloy round tube is installed at the tail. The inner diameter of the round tube is 0.001m 2 ;

[0042] f) The shape of the ventral fin and the titanium alloy oil drain port are rectified to minimize the resistance generated by the oil drain passage.

Claims

1. A method for designing an air oil discharge channel for oil discharge through the aircraft ventral fin, characterized in that: The steps include: a. Select an oil tank as the oil drain tank and install an oil pump in the oil drain tank; b. Extend the oil pipe from the oil drain tank as the engine body oil drain pipeline, and install an oil drain cut-off valve on the engine body oil drain pipeline; c. Arrange and fix the oil drain pipe along the frame, and connect the outlet of the oil drain pipe to the inlet of the ventral fin oil drain channel (2) in the ventral fin at the root rib of the ventral fin (1) through a flange; d. Calculate the internal cross-sectional area requirements of the fuselage oil discharge pipeline and ventral fin oil discharge channel according to the oil discharge speed requirements; e. Design the outlet of the ventral fin oil drain channel at the rear edge of the ventral fin.

2. The method for designing an aerial oil discharge channel for oil discharge through the aircraft ventral fin according to claim 1, characterized in that: In step c, when the engine body oil drain pipeline is arranged and fixed along the engine body frame, the distance between two adjacent stress points on the engine body oil drain pipeline is not greater than 700 mm.

3. The method for designing an aerial oil discharge channel through the aircraft ventral fin according to claim 1, characterized in that: In step c, when the engine body oil drain pipeline needs to pass through the reinforcement frame of the engine body, a hole is opened on the reinforcement frame, and the engine body oil drain pipeline passes through the reinforcement frame and is fixed by a flange.

4. The method for designing an aerial oil discharge channel through the aircraft ventral fin according to claim 1, characterized in that: In step c, when the engine body oil drain pipeline needs to pass through the common frame and / or half frame of the engine body, the common frame and / or half frame are partially or completely reinforced, and the engine body oil drain pipeline is connected to the common frame and / or half frame through a clamp.

5. The method for designing an aerial oil discharge channel for oil discharge through the aircraft ventral fin according to claim 1, characterized in that: In step c, the ventral fin oil discharge channel and the ventral fin are designed in a fusion style.

6. The method for designing an aerial oil discharge channel for oil discharge through the aircraft ventral fin according to claim 1, characterized in that: In step c, the ventral fin oil discharge channel is tilted downward as a whole, with a downward tilt angle of 3 to 6 degrees.

7. The method for designing an aerial oil discharge channel for oil discharge through the aircraft ventral fin according to claim 1, characterized in that: In step e, a titanium alloy oil drain port (3) is designed at the outlet of the ventral fin oil drain channel at the rear edge of the ventral fin.

8. The method for designing an aerial oil discharge channel for oil discharge through the aircraft ventral fin according to claim 7, characterized in that: The length of the titanium alloy oil drain port (3) is 8 to 15 cm.

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